This application claims the priority benefit of Taiwan application Ser. No. 91220267, filed on Dec. 13, 2002.
1. Field of Invention
The present invention relates to a flip chip package structure, and more particularly, to a flip chip package structure with an area bump.
2. Description of Related Art
The flip chip interconnect technology mainly disposes a plurality of bonding pads (also known as die pads) on an active surface of a chip (also known as a die) by using an area array layout method, and forms a bump on each bonding pad. After the chip is flipped, the bumps on the bonding pads of the chip are respectively electrically and mechanically connected to the contact pads, which correspond to the surface of a substrate or a Printed Circuit Board (PCB). Further, the flip chip interconnect technology also forms the bumps on the contact pads of the surface of the substrate or the PCB first, and electrically and mechanically connected to their corresponding bumps via the bonding pads on the active surface of the chip, respectively. It needs to be noted that since the flip chip interconnect technology can be applied in the high pin count chip package structure and is advantageous in reducing the package area and shorten the signal transmission path, the flip chip interconnect technology has been widely applied in the chip package field currently. The most common used chip package structures applying the flip chip interconnect technology comprise the chip package structures, such as the Flip Chip Ball Grid Array (FC/BGA) and the Flip Chip Pin Grid Array (FC/PGA).
Referring to both FIG. 1 and FIG. 2, FIG. 1 schematically shows a top view of a conventional flip chip package structure, and FIG. 2 schematically shows a sectional view cut from the Ixe2x80x94I line in FIG. 1. The flip chip package structure 100 comprises a substrate 110, a chip 130, and a plurality of bumps 140. As shown in FIG. 2, the substrate 110 comprises a substrate surface 112 and a plurality of contact pads 114, wherein the contact pads 114 are disposed on the substrate surface 112 of the substrate 110. Further, the chip 130 comprises an active surface 132, wherein the active surface 132 of the chip 130 roughly means the surface on which the active devices (not shown) are disposed. The chip 130 further comprises a plurality of bonding pads 134, which disposed on the active surface 132 of the chip 130 and used as a media for input/output the signal of chip 130. The contact pads 114 are correspondingly disposed on the bonding pads 134, respectively. Further, the bumps 140 electrically and mechanically connect one of the bonding pads 134 to one of its corresponding contact pads 114, respectively. Finally, an underfill 150 is filled into the cavity surrounded by the substrate 110, the chip 130, and the bumps 140, so as to protect the exposed portion of the contact pads 114, the bonding pads 134, and the bumps 140.
Regarding to the conventional flip chip interconnect technology, the bonding pads of the chip, which provide the functions of signal, power and ground, are electrically and mechanically connected to their corresponding contact pads of the substrate via the same size ball bumps, respectively. It needs to be noted that the electrical performance and the heat dissipation performance are constant for the same size bumps, thus it is hardly achieved the object of improving the electrical performance and the heat dissipation performance by using the same size bumps after the chip is packaged. Therefore, if the designer intends to significantly improve the electrical performance and the heat dissipation performance after the chip is packaged, a new structure has to be developed.
It is an object of the present invention to provide a flip chip package structure with an area bump, in which the bump can be designed as any shape in its cross direction based on the special electrical requirement of the chip, so as to improve the electrical performance and the heat dissipation performance after the chip is packaged.
A flip chip package structure with an area bump provided by the present invention comprises a substrate, at least a chip, a plurality of first bumps (normal bumps), and at least a second bump (area bump). The substrate comprises a substrate surface, a plurality of first contact pads, and at least a second contact pad, wherein the size of the second contact pad is larger than one of the first contact pads. The chip further comprises an active surface, a plurality of first bonding pads, and at least a second bonding pad, wherein the size of the second bonding pad is larger than one of the first bonding pads. The first bump is respectively connected to one of the first bonding pads and the corresponding one of the first contact pads. Further, the second bump is connected to the second bonding pad and the second contact pad, wherein the size of the second bump is larger than one of the first bumps.
In accordance with the preferred embodiment of the present invention, the size of the second bump can be two times of size of one of the first bumps. Further, the first bumps can be disposed on the periphery of the second bump, wherein the first bonding pad may be such as the signal bonding pad, the power bonding pad, or the ground bonding pad, and the second bonding pad may be such as the power bonding pad, the ground bonding pad, or the special signal bonding pad. Furthermore, an underfill is filled into the cavity surrounded by the chip, the first bumps, the second bumps, and the substrate.
Therefore, with the flip chip package structure with an area bump provided by the present invention, multiple bumps in the same group originally connected to the power or ground are integrated into a bump by changing the shape of the bump in its cross direction, so as to increase the electric conductive area and the heat dissipation area for the multiple bumps before they are integrated, and further improve the electrical performance and the heat dissipation performance after the chip is packaged.